Reenforced circulating coil



July 7, 1931. A. FRIEDMAN 1,813,891

REENFORCED 'CIRCULATING COIL Filed Feb. -27. 1928 Patented July 7, 1931,UNITED STATES PATENT OFFICE ARTH'UR FRIEDMAN, OF CLEVELAND, OHIG,ASSIGNOR TO THE CLEVELAND HEAT-ER 1 COMPANY, OI CLEVELAND, OHIO, ACORPORATION OF OHIQ i REENI'ORCED GIRGULATING COIL Application flledlebruary 27, 1928. Serial 1T0. 257,222.

This invention relates to improvements in gas burning liquid heaters andin particular to the circulating coils used in gas burning domesticwater heaters. I 7

It has for its object the provision of a water heating circulating coilthat is inexpensive and easy to manufacture, and that is more 1 durablethan the ordinary type of circulating coil, and that is re-enforced andprotected against the destructive action of the condensation formedthereon from the productsof combustion of the gaseous fuels commonlyused in gas burning water heaters.

My invention in general consists in the provision of adouble section oftubing which constitutes'that portion of the heater coil terminatinginthelower coil coupling. This l e-enforcement in general extends aboutthree or four inches from the coupling and is placed 'three for thepurpose of strengthening the recoil, at this point, against thecorrosive action ofthe liquids which condense on the heater coils andeventually find their way to the lowest portion ofthe heater coilscollectingat the junction of the coils and the coupling. 1 Y In copperheater coils of the, ordinary type there is a decided tendency for thecoils to fail at the point where they enter the lower Coupling member.This failure of the coils is due to the disintegration of the copperfrom which thecoils are made, and is usually accompanied by theformation of copper. sulphate or other decomposition compounds at thepoint offailure at the coil. It is common knowledge that many commercialgases, particularly manufactured gas, upon burning give off an oxide ofsulphur as well as water vapor, 7

he accepted theory ofthis phenomena observed in gas fired water heatersis that the condensation of watervapor which takes place on the heatercoils, causes the formation of .ik sulphurous acid by combining with thesul- :phur dioxide/given oil by the'burning gas.

As the weak sulph'urous acid thus formed on the heater coils runs to thebottom of the coils, a certain amount of it is converted into sulphuricacid, by reason of coming in contact with what copper oxide may bepresent on the heatercoils.

The dilute acids thus formed collect at the lowermost point of thecoils, which is where they enter the bottom coil coupling. At this pointthere is apt to be present considerable copper oxide if it is a brazedjoint. oxide referred to is present as a result of the action of the gasflame used in the brazing operation. f

Furthermore, the copper tubing at the brazed joint is somewhat weakened,due to the heat applied in brazing, which causes some oxidation as wellas annealing, both of which are apt to leave this portion of thejointbetween the tubing and the coupling,

whether it be a brazed joint or a union coupling, it is apparent that apart of the aforementioned liquids, condensed from'the products ofcombustion of the gaseous fuel, come to rest at the junction of thecoupling and the coils. I

At this junction point, which is in close proximity to the heaterburner, the condensation products are further concentrated by directaction of the flame and evaporation of excess water in the acidsolutions producing concentrated sulphuric acid, which readily combineswith the copper of the heater coil.

It is upon thistheory, which is supported by the presence of coppersulphate at the The lower extremities with a short r-e-enforcinginterior of the heater coils accelerates their deterioration. Underthese conditions, when in operation, the heater coils are kept at a muchhigher degree of temperature, due to the low thermal conductivity of thefouled tubing, and in addition to being more rapidly disintegrated bysulphuric acid, the coils are also oxidized by the direct action of theburner flame.

The primary object of this invention is to re-enforce that part of theheater coil which is most apt to be attacked by the aforementionedcondensation products of combustion.

This result is accomplished in my improved coil by the provision ofanextra section of tubing over the last few inches of the lower portionof the coils. By this arrangement the coil is materially strengthened atthis point and its useful life should be materially lengthened thereby.

This invention is particularly useful in water heaters in which the endsof the circulating coil are brazed in the coil coupling member, as thecoils are somewhat weakened by this operation, due to the high heatwhich "is applied to them, and to the action of the fluxes which areused in brazing.

In the accompanying drawings Fig. 1 shows a front elevation, partly insection, of a water heater constructed in accordance with, and adaptedfor use in practising my invention. Fig. 2 is a plan elevational viewpartly in section of the coil coupling and the coil re-enforcing member.

Referring to the drawings, the reference numeral 1, indicates the heatercasing or jacket of a conventional gas fired domestic water heater. Thiscasing provides a housing for the copper circulating coils 2 which areadapted to be put into communication with a storage vessel or tank bymeans of the low-er and upper union-connections 3 and 4, respectively. 7

Means for applying heat to the coils is provided for by the gas burner5, which'is mounted on an air and gas mixing tube 7,

of the Venturi type. Theburner 5 is positioned below the coils in thelowerportion of the heater jacket. A gas cook 8 is mounted at the inletend of the mixing tube 7, and is adapted to be connected to a source ofgas supply.

he heater coils 2 are provided at their section 9, of tubing which isadapted to be secured in the couplingmember 6 by any suitable methodsuch as brazing. The joint 10 between the overlapping re-enforcingsection and'the coil to which it is applied may also be effected bybrazing. i

The ire-enforcing sections 9 may be formed independently of the coils 2and then slipped over the coils before the brazing operation, ortheymaybe formed by the same operation that is used in forming coils 2.The sections 9, if so desired, may be made of heavier gauge tubing thanthe coils 2. The coils 2 may be made to terminate a short distance fromthe joint 10 instead of extending to the end of the re-enforcingsections 9. As shown in the drawings, the joint 10 of the coil sections2 and 9 joins these portions of the coil to each other with a smoothlybevelled joint so that there will be no tendency for the collection ofcondensate at this point.

It is apparent from the foregoing that this type of re-enforcement willmaterially lengthen the life of the coils and protect them againstsulphation, as well as, oxidation by the flame of the burner 5, which isapt to happen in casethe interior of the coils becomes covered withscale.

It is apparent that my improved heater coil could be used in conjunctionwith oil burning water heaters as well as gas burning Having describedmy invention, I claim:

: 1. In a water heater, a vertically arranged tubular circulating coil,a coupling member for the lower end of said coil, heating means locatedbelow said coil, and coil re-enforcing means comprising a relativelyshort'section of tubing providing a protective. sheath that encompassesthe lower end portion of said coil to protect said coil. at the pointwhere it enters said coupling fromthe corrosiveaction of condensatedeposited on said coil and collected at this point.

2. In aliquid heater, a vertically arranged tubular circulating coil,means for supply ing heat to said coil, a relatively short re-enforcingsleeve positioned on the lower end portion-of said coil to protect thesame against the corrosive action of condensate collected on the coil atthis point, and a coupling member'connected in fluid tight relation tothe end portion of said sleeve and coil.

3. In a'liquid heater, a vertically arranged tubular circulating coilterminating in a double walled portion of less than 40i a coil turn atits lower extremity, means for supplying heat to said coil, and acoupling member brazed to the lower end of said coil,

said double walled portion of the coil being adapted to strengthen thecoil against the corrosive action of condensate collected at thejunction of said coupling and coil.

4. In a liquid heater, means for supplying heat thereto, a verticallyarranged tubular circulating coil formed from a piece of metal tubing,at protecting sleeve formed from a relatively short section of tubing ofsimilar material and of larger diameter than the coil tubin fitted overthe lower end portion of the tufiing of said coil, and a coupling memberreceiving and brazed to the end of said coil and sleeve, said sleevestrengthening the junction of said coupling and coil.

In testimony whereof I afiix my signature.

ARTHUR FRIEDMAN.

